This The “My Mailers” option under Campaigns is where you can upload your own images to print with MSM. See template below for what with MyShopManager and use a Direct Mail campaign. This allows you to use your own designs with the printing of a MyShopManager campaign.
See the template below for a guide to the size that is needed. Anything outside the template will not show correctly and is not guaranteed to print correctly.
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For more information on MyShopManager Direct Mail campaigns see What is direct mail?